Steel melting and more particularly gas fired regenerative furnaces



Oct. 3, 1967 s. M. ANDONJEV ETAL STEEL MELTING AND MORE PARTICULARLY GAS1 FIRED REGENERATIVE FURNACES Filed July 18, 1965 5 Sheets-Sheet l Oct.3, 1967 s. M. ANDONJEV- ET AL v STEEL MELTING AND MORE PARTICULARLY GASFIRED REGEHERATIVE FURNACES 3 Sheets-Sheet 2 Filed July 18, 1963 1967 s.M. ANDONJEV ETAL 3,345,054

STEEL MELTING AND MORE PARTICULARLY GAS FIRED REGENERATIVE FURNACES 5Sheets-Sheet 5 Filed July 18, 1965 United States Patent Ofiice 3,345,054Patented Oct. 3, 1967 3,345,054 STEEL MELTING AND MORE PARTICULARLY GASFIRED REGENERATIVE FURNACES Sergei Mikhailovich Andonjev, Kharkov, PetrGerasimovich Glazkov, Donetsk, Vladimir Alexandrovieh Kuchiu, Kharkov,Konstantin Ivanovich Makarov, Moscow, Nickolai Ivanovich Pevny andAlexandr Markovich Pochtman, Kharkov, Pavel Alexandrovich Tesner,Moscow, and Oleg Vladimirovich Filipjev, Kharkov, U.S.S.R., assignors toGosudarstvenny Nauchno-Issledovatelsky i Proektny InstituteMetallurgicheskoi Promyshlennosti Filed July 18, 1963, Ser. No. 295,8868 Claims. (Cl. 26633) The present invention relates to the art of steelmelting and, more particularly, to gas fired regenerative furnaces.

More specifically the invention relates to open-hearth furnaces firedwith cold high calorific gas, such as natural or coke gas or mixturethereof.

The invention can be implemented in any industrial branch requiring aluminous flame of natural gas Without introducing liquid fuel therein.

The known regenerative furnaces fired with natural gas with a highlyluminous flame at each heated side contain a firing throat, air and gasregenerators, conduits for feeding hot gases and air from theregenerators to the firing throat, a burner in each firing throat, achamber positioned within the furnace for a preliminary cracking ofnatural gas thereby obtaining carbon particles, and means for feedinggas and oxidizer into the chamber.

The chambers in the known furnaces are designed for the cracking processof natural gas in order to obtain carbon particles and the yield ofcarbon particles is inadequate as well as the velocity of the gascarrying the carbon particles from the chamber being low andinsufiicient to create the high gas velocities necessary in theopen-hearth furnaces and inadequate to direct the flame torch to thesurface of the steel to be melted. In addition, there is an inadequateor no control over the quantity and size of the carbon particles.

The chambers in such furnaces for a preliminary cracking of natural gasare arranged inside the furnace, thus making the furnace design andrepair rather complex together with increased costs for production andoperation.

An object of the present invention is to create a flame of natural gaswith a high and controlled luminosity with the flame having a highvelocity and being directed at the surface of the steel to be melted.

Another object of the invention is to increase the useful space of thehearth in the known operating furnaces and augment the output thereofwithout any change in the overall furnace dimensions, by the eliminationof the channels and feeding of the gas from the gas regenerators to thefiring throat, since the regenerative gas-heating process is eliminated.Still another object of the present invention is to use the heat givenup by fuel gases in the air regenerator and the pressure of the naturalgas which is introduced for the heating of the furnace.

To accomplish the above and other objects, the regenerative furnace isfired by natural gas with high and controlled luminosity and comprisesfiring throats located at each fired side, air regenerators, conduitsfor supplying hot air from the regenerators to the firing throat, burnermeans arranged in the firing throat, a chamber for a partial combustionof a part of the natural gas and obtaining carbon particles with thechamber being connected to the firing throat and means for feeding gasand oxidizer into the chamber.

Such feeding means are in the form of a branch pipe for the axialfeeding of gas and the tangential feeding of air, or in the form of adevice for mixing gas and oxygen positioned at the chamber inlet. Thechamber can be positioned both in the firing throat and outside of thefurnace and located either coaxially with or at an angle to the axis ofthe burner.

The use of the heat given up by the fuel gases in the air regeneratorcan be effected by means of connecting the conduits for the hot air withthe branch-pipe for the tangential feeding of air into the chamberthrough a pipe having a jet orifice for injecting the hot air from theregenerator by compressed air supplied from any suitable source.

The implementation of the natural gas for feeding coke gas, if thelatter is used for furnace heating and is fed at low pressure, ispossible by means of a jet fixed on the branch pipe feeding the coke gasto the burner means and the jet is connected with natural gas fed athigh pressure.

Further objects and advantages will become readily apparent to personsskilled in the art from the following detailed specification andaccompanying drawings, in which drawings:

FIG. 1 is a diagrammatic view partly in elevation and partly in crosssection of a heated side of an open-hearth furnace and the chamber forthe partial combustion natural gas arranged according to the presentinvention vertically and outside of the furnace;

FIG. 2 is a fragmentary view partly in elevation and partly in crosssection of the firing throat and the chamber for the partial combustionof natural gas arranged outside the furnace co-axially with the burnermeans.

FIG. 3 is a view partly in elevation and partly in cross section of thechamber for the partial combustion of the natural gas and the burnermeans connected co-axiall with the chamber.

FIG. 4 is a vertical sectional view of the firing throat and theco-axially arranged chamber for the partial combustion of natural gasand burner means positioned in the throat; and

FIG. 5 is a fragmentary view partly in elevation and partly in crosssection of the firing throat and the burner means positioned thereinconnected with the chamber for the partial combustion of the natural gaswhen it is placed at an angle to the axis of the burner outside thefurnace.

As disclosed in FIG. 1, a regenerative furnace 1 adapted to be fired bynatural gas with high and controlled luminosity at each fired sidethereof is provided with a firing throat 2, air regenerator 3, a duct 4for supplying hot air from the regenerator 3 to the firing throat 2,burner means 5 arranged in the throat 2, a chamber 6 for the partialcombustion of the natural gas and for obtaining free carbon. The chamber6 is located exteriorly of the furnace and is connected with the burnermeans 5. In FIG. 1, it will be seen that the chamber 6 is positioned atan angle to the burner 5.

A casing 8 of the chamber 6 is provided with an end lid or cap 7carrying a branch-pipe 9 serving for the axial feeding of a natural gasinto the chamber 6. The side wall of the casing 8 supports a branch-pipe10 for the tangential supply of air for the chamber 6.

A conduit 11 connects the duct 4 with the branch-pipe 10 and is providedwith a jet orifice 12 which is supplied With compressed air in thedirection shown by arrowhead R from a compressor (not shown). Thecompressed air serves for injecting hot air from the duct 4 and forfeeding the resulting hot air mixture under pressure through thebranch-pipe 10 into the chamber 6, with the pressure exceedingatmospheric pressure.

In addition to the means above described, air can be introduced into thechamber 6 in a cold condition or enriched by oxygen by means known topersons skilled in the art. The hot gaseous products of partialcombustion are fed from the chamber 6 through the burner means into thefurnace *1 and contain mainly carbon particles serving for the flameluminosity. The products of partial combustion may contain none or anegligible amount of acetylene.

By controlling the volume of the air which is introduced through thebranch-pipe 10 into the chamber 6, it it is possible to vary thequantity and size of the carbon particles resulting from a partialcombustion of a part of the natural gas supplied for the heating of thefurnace and the same means functions to control the flame luminosity.

By controlling the pressure of the gas and air introduced into thechamber 6 for the partial combustion process, the velocity of theproducts of partial combustion fed into the furnace 1 through the burnermeans 5 having corresponding cross-section dimensions can be influenced.In this burner means, the hot products of the partial combustion of thenatural gas are mixed with the rest of the natural gas and coke gas aswell if such latter gas is applied for the heating of the furnace.

As shown in FIG. 2, a branch-pipe 13 supplies coke gas from a conduit 14to the burner means 5 and is provided with a jet 15 supplied with anatural gas under high pressure through a branch-pipe 16 from the mainpipeline (not shown). This gas functions for the highspeed injection ofthe coke gas into the furnace 1 through the burner means 5.

Referring to FIG. 3, it can be seen that the burner 5 is a unit providedwith a water jacket 17 equipped with a water-feed pipe 18 and awater-discharge pipe 19. The water jacket 17 is lined with refractorymaterial, such as brick 20, which provides a channel 21 for conducting amixture of gases consisting of the products of partial combustion of apart of the natural gas, the remaining part of natural gas and coke gas,in case such latter gas is used into the furnace 1. The design of theburner 5 is such as to supply oxygen or steam through ducts 25 which canbe positioned outside of the burner casing as shown in FIG. 5 and thesaid oxygen and water serve to intensify the melting process.

As illustrated in FIG. 4, when the chamber 6 and burner 5 are positionedin the firing throat 2 of the furnace 1, a common water-cooled jacket 26is employed. The jacket includes a pipe 27 and a water-discharge pipe28, as well as ducts 29 which introduce oxygen or water steam into thefurnace 1 for intensifying the steel melting process. FIG. 3 illustratesa variant of the chamber 6 in which oxygen is used as an oxidizer forthe partiazl combustion process with the oxygen being initially mixedwith the natural gas in unit 22. The oxygen is fed into the unit 22through a branch-pipe 23, while the natural gas is fed through abranch-pipe 24.

When oxygen is used as an oxidizer, there are created in the chamber 6,hot products of the partial combustion of the natural gas containingcarbon particles and, mainly, acetylene, which is easily decomposed andcreates carbon particles in the flame torch of the furnace 1.

As shown in FIG. 3, the casing 8 of the chamber 6 .is equipped with arefractory brick lining 30. To maintain the temperature of the dining ata level ensuring a reliable ignition of the gas and oxidizer mixture inthe chamber 6 after the fire in the furnace 1 is directed to anothersize, a small amount of the natural gas and oxidizer is continuouslyintroduced into the chamber 6. For this purpose, natural gas is fed by abranch-pipe 31 and compressed air by branch-pipe 32. Aperture 33 in thelining of the chamber 6 serves for collecting analysis samples of theproducts of partial combustion and visual control of the combustionprocess within the chamber 6 is effected through an inspection hole 34.In order to provide a connection with the burner means 5, the lining 30of chamber 6 is in the form of a cone 3S and thermocouple 36 measuresthe temperature.

Referring to FIG. 5, it will be seen that the chamber 6 is positionedoutside of the furnace at an angle to the axis of burner 5 and thechamber 6 is connected with the burner 5 by means of an elbow jacket 37provided with an inner refractory brick lining (not shown).

The jacket 37 is equipped with a branch-pipe 38 having a removable lidor cover 39 and the pipe 38 serves for cleaning the channel 21 of theburner means 5 from solid litter particles which may collect from thefurnace 1 as well as for collecting samples of the partial combustionproducts from the chamber 6'. Moreover, the pipe 38 can be used for theinstallation of an inspection hole.

When the furnace is in operation, the natural gas and oxidizer areintroduced into the chamber 6 in which the products of partialcombustion having a temperature about 1200 C. and containing acetyleneand/ or carbon particles depending on whether oxygen or air has beenused as an oxidizer are obtained and the oxidizer is supplied in anamount insuflicient for the complete combustion of the mixture. From thechamber 6 the products of partial combustion are directed to the burnermeans 5 in which they are mixed with the remaining part of the naturaland coke gas, if the latter gas is used.

The gas and oxidizer pressure at the inlet of the chamber 6 and thepressure of the natural and coke gases at the inlet of the burner means5 exceed the mean atmospheric pressure and the pressure is so selectedas to overcome the resistance against the gas stream on its travel tothe furnace 1 and create a fuel gas speed not less than 50 in. persecond at the burner outlet.

The quantity of carbon particles supplied for the flame luminosity iseasily controlled by changing the volume of the oxidizer introduced intothe chamber 6 for the partial combustion process. The flame luminositycan be regulated by changing the volume of the gas as well but thecontrol with the aid of changing the amount of an oxidizer ispreferable. Additional checking of the partial combustion process in thechamber 6 is by measurements taken by the thermocouple 36.

Prior to the starting of the furnace, the lining of the chamber 6 iswarmed by a complete burning therein of some natural gas and acorresponding amount of air. The gas and air are fed even when thefurnace firing is transferred to another size and the gas and oxidizerfeed for the partial combustion process at such side is arrested. Whenthe chamber resumes its operation at this side, the burning of the smallquantity of gas therein results in a reliable ignition of the gassupplied for a partial combustion.

The invention is not to be confined to any strict conformity to theshowings in the drawings but changes or modifications may be madetherein so long as such changes or modifications mark no materialdeparture from the spirit and scope of the appended claims.

What we claim is:

1. A regenerative furnace fired by a natural gas with a high andluminous flame, comprising a firing throat, air regenerators, conduitsfor feeding hot air from the regenerators to the firing throat, burnermeans arranged in the firing throat, means constituting a chamber for apartial combustion of a part of the natural gas accompanied by creatingcarbon particles, means connecting the chamber with the burner means,and means for feeding gas and oxidizer into the chamber.

2. The regenerative furnace as claimed in claim 1 in which said chamberis positioned coaxially with respect to the burner means.

3. A regenerative furnace as claimed in claim 1 in which said chamber ispositioned at an angle with respect to the burner means.

4. A regenerative furnace fired by a natural gas with a high andregulated flame luminosity, comprising a firing throat, airregenerators, conduits for feeding hot air from the regenerators to thefiring throat, burner means arranged in the firing throat, meansconstituting a chamber for a partial combustion of a part of the naturalgas accompanied by creating carbon particles, means connecting thechamber with the burner means, a branch-pipe for axial introduction of anatural gas located at one end of the chamber and a branch-pipe fortangential air supply to the chamber located on the side wall of thechamher.

5. A regenerative furnace fired by a natural gas with a high andregulated flame luminosity comprising a firing throat, air regenerators,conduits for feeding hot air from the regenerators to the firing throat,a burner means arranged in the firing throat, means constituting achamber for a partial combustion of a part of the natural gasaccompanied by creating acetylene and carbon particles, means connectingthe chamber With the burner means, and a device for mixing the naturalgas fed into the cham- -ber with oxygen.

6. A regenerative furnace fired by a natural gas With a high andregulated flame luminosity, comprising a firing throat, airregenerators, conduits for feeding hot air from the regenerators to thefiring throat, burner means arranged in the firing throat, meansconstituting a chamber for a partial combustion of a part of the naturalgas accompanied by creating carbon particles positioned outside thefurnace, means connecting the chamber with the burner means, abranch-pipe for tangential air supply to the chamber located on the sideWall of the chamber.

7. A regenerative furnace as claimed in claim 6 including a conduit forfeeding hot air to the firing throat, a

pipe connecting the conduit with the branch-pipe for the tangential airsupply, a jet for the pipe, and means for feeding air under pressure tothe pipe.

8. A regenerative furnace fired by a mixture of natural and coke gas,comprising a firing throat, air regenerators, conduits for feeding hotair from the regene-rators to the firing throat, means constituting achamber for a partial combustion of a part of the natural gas positionedoutside the furnace, means for feeding gas and oxidizer into thechamber, means for feeding the products of partial combustion from thechamber to the burner means, a branch-pipe for supplying coke gas to theburner means, and a jet in the branch-pipe for feeding natural gas atpressure to the burner means.

References Cited UNITED STATES PATENTS 1,933,571 11/1933 Trinks 263152,056,531 10/1936 Morton 26315 2,287,785 6/1942 Dean 263-15 2,298,84210/1942 Richardson 26315 JOHN F. CAMPBELL, Primary Examiner.

R. F. DROPKIN, P. M. COHEN,

Assistant Examiners.

1. A REGENERATIVE FURNACE FIRED BY A NATURAL GAS WITH A HIGH ANDLUMINOUS FLAME, COMPRISING A FIRING THROAT, AIR REGENERATORS, CONDUITSFOR FEEDING HOT AIR FROM THE REGENERATORS TO THE FIRING THROAT, BURNERMEANS ARRANGED IN THE FIRING THROAT, MEANS CONSTITUTING A CHAMBER FOR APARTIAL COMBUSTION OF A PART OF THE NATURAL GAS ACCOMPANIED BY CREATINGCARBON PARTICLES, MEANS CONNECTING THE CHAMBER WITH THE BURNER MEANS,AND MEANS FOR FEEDING GAS AND OXIDIZER INTO THE CHAMBER.